The present invention relates to a multiple cylinder rotary compressor and more particularly to a hermetically sealed multiple cylinder compressor including new and improved means for controlling refrigeration capacity.
Heretofore, such an apparatus as shown in FIG. 17 has been proposed by, for example, Japanese Utility Model Publication No. 46-5964, published Mar. 3, 1971 as a single cylinder type rotary compressor. In FIG. 17, a rotary compressor 1 has a cylinder block 4 having a cylinder 3 concentric to a driving shaft 2, a rotor 6 rotated along an inner circumferential surface of the cylinder 3, a vane 10 which is pressed against an outer surface of the rotor 6 by a coil spring 7 to divide the cylinder 3 into a suction side 8 and a compression side 9 and suction opening 11 located at one side of the vane 10 to connect with the suction side 8 and a discharge opening 12 which is provided at the other side of the vane 10. The suction opening 11 is connected to a suction pipe 13. The compression side 9 is connected through the discharge opening 12 to a discharge port or muffler 14, which is formed in the cylinder block 4 and has a discharge valve 15 to open and close the discharge opening 12. The cylinder block 4 has a gas-release slot 16 at a portion distal to the suction opening 11 so that the cylinder 3 is communicated to the suction side, which is communicated to the suction opening 11, by the gas-release slot 16. In the conventional rotary compressor described above, when a gas flown from the suction opening 11 to the suction side 8 is compressed by rotation of the rotor 6 in an initial compression stroke, the gas is partly released out of the gas-release slot 16 to cause a delay of compression, so that a refrigeration capacity is controlled.
However, the above-described conventional rotary compressor has disadvantages as described hereinbelow. Namely, the gas flown from the suction opening 11 into the cylinder 3 is partly discharged out of the cylinder 3 and, accordingly, a suitable shielding device must be used so that the gas-release slot 16 is not connected to the discharge muffler 14, and therefore the structure becomes complex. Further, in case of a multiple cylinder rotary compressor, a plurality of gas-release slots must be formed for the cylinders and, accordingly, manufacturing and assembling steps become complex.
Japanese Utility Model Publication No. 55-15009, published Apr. 7, 1980, shows another rotary compressor as illustrated in FIG. 18, which is somewhat similar to the first-mentioned conventional rotary compressor shown in FIG. 17. For example, rotary compressor 1 has a rotor 6, suction side 8, pressure side 9, vane 10, and discharge valve 15. Various differences are described hereinbelow. In the structure of FIG. 18, a controller 19 is disposed on the cylinder block 4 at the portion opposite to the position of discharge opening 12. The controller 19 has a guide hole 20 at the cylinder wall, and a capacity controlling valve 21 in a controlling chamber 22 to open and close the guide hole 20. The controlling chamber 22 is connected to a controlling tube 23, which is selectively connected to an outlet of a condenser 25 and a suction tube 13 of an outlet of an evaporator 26, by means of a three-way valve 24. In FIG. 18, reference numeral 27 is a capillary tube connected between the condenser 25 and the evaporator 26. In this conventional rotary compressor, the capacity controlling valve 21 is controlled by either a high-pressure refrigerant from the outlet of the condenser 25 or a low-pressure refrigerant from the outlet of the evaporator 26 by means of the three-way valve 24, and a refrigeration capacity of the rotary compressor 1 is controlled by the operation of the capacity controlling valve 21.
Further, in this second conventional rotary compressor, the low-pressure refrigerant is effected on the controlling chamber 22 by the three-way valve to thereby open the capacity controlling valve 21, and the refrigerant flown from the suction opening 11 into the cylinder 3 is partly returned from the controlling tube 23 to the suction tube 13. Therefore, a pulsating refrigerant is flown through the controlling tube 23, generating vibration and/or noise, and a relatively large-diameter tube must be installed for returning the refrigerant.